X-rays have traditionally been used in the medical industry to view bone, tissue and teeth. X-rays have also been used to treat cancerous and precancerous conditions by exposing a patient to x-rays using an external x-ray source. Treatment of cancer with x-rays presents many well documented side effects, many of which are due to the broad exposure of the patient to the therapeutic x-rays.
To minimize patient trauma, minimally invasive endoscopic techniques have been developed and are used to treat a variety of conditions. Endoluminal procedures are performed with an endoscope, a tubular device into the lumen of which may be inserted a variety of rigid or flexible tools to treat or diagnose a patient""s condition.
The desire for improved minimally invasive medical devices and techniques have led to the development of miniaturized x-ray devices that may be used in the treatment or prevention of a variety of medical conditions. International Publication No. WO 98/48899 discloses a miniature x-ray unit having an anode and cathode separated by a vacuum gap positioned inside a metal housing. The anode includes a base portion and a projecting portion. The x-ray unit is insulated and connected to a coaxial cable which, in turn, is connected to the power source. An x-ray window surrounds the projecting portion of the anode and the cathode so that the x-rays can exit the unit. The x-ray unit is sized for intra-vascular insertion, and may be used, inter alia, in vascular brachytherapy of coronary arteries, particularly after balloon angioplasty.
International Publication No. WO 97/07740 discloses an x-ray catheter having a catheter shaft with an x-ray unit attached to the distal end of the catheter shaft. The x-ray unit comprises an anode and a cathode coupled to an insulator to define a vacuum chamber. The x-ray unit is coupled to a voltage source via a coaxial cable. The x-ray unit can have a diameter of less than 4 mm and a length of less than about 15 mm, and can be used in conjunction with coronary angioplasty to prevent restenosis.
Miniaturized x-rays are not foolproof, however, and present difficulties problems which must be considered and addressed. The x-ray unit generates heat, which can damage adjacent tissue. Additionally, x-rays are not localized and irradiate local tissue rather than only irradiating the desired site. Also, it is difficult to maintain the positioning of these instruments inside at the desired location. Improved miniaturized x-ray units which overcome these difficulties are desirable.
Other techniques are used to treat tumors with x-rays, including planting a seed of radioactive material at the tumor site (brachy therapy), typically accomplished with endoluminal procedures. However, the patient becomes xe2x80x9chotxe2x80x9d, i.e., radioactive, and the procedure risks exposure of the medical personnel to radiation exposure.
In all x-ray procedures, over radiation of the patent is a concern. U.S. Pat. No. 5,127,394 discloses a fluoroscopy-switching device and a method for preventing accidental over radiation of a patient in surgical procedures involving both fluoroscopy and endoscopy. Video outputs from the endoscope and fluoroscope are connected to a switching device. The endoscope generates a video signal having a first video format, and the fluoroscope generates a video signal having a second video format. The physician uses the switching device to select from between the endoscope video output and the fluoroscope video output for viewing on a video monitor which accepts a video signal of a predetermined video format. The switching device is operable to convert at least one of the endoscope video signal or the fluoroscope video signal to the predetermined video format, which the monitor accepts. When the endoscope video output is selected for viewing, the switching device automatically deactivates the X-ray generator of the fluoroscope. When the switching device is actuated to select the fluoroscope video signal for viewing on the monitor, the switching device automatically reactivates the x-ray generator to avoid exposing the patient to excessive radiation during periods when the fluoroscope is not being used.
U.S. Pat. No. 5,993,404 also describes a fluoroscopy-switching device and method for preventing accidental over radiation of a patient in surgical procedures involving both fluoroscopy and endoscopy. Video outputs from the fluoroscope and endoscope are connected to a switching device. The physician uses the switching device to select from between the endoscope video output and the fluoroscope video output for viewing on a video monitor. When the endoscope video output is selected for viewing, the switching device automatically deactivates the X-ray generator of the fluoroscope. When the switching device is actuated to select the fluoroscope video signal for viewing on the monitor, the switching device automatically reactivates the x-ray generator to avoid exposure to excessive radiation when the fluoroscope is not being used.
One difficulty is that a guide wire is desirable to permit proper positioning of the x-ray device in the lumen. However, it is difficult to coordinate alignment of the guide wire and x-ray source at the desired site, and guide wires are typically made of metallic materials which can impede the irradiation of the target tissue by creating a xe2x80x9ccold spotxe2x80x9d where the x-rays are blocked by the guide wire.
A problem with endoscopy in general is correctly positioning the device in a body lumen. U.S. Pat. No. 5,084,061 describes an intragastric balloon with improved valve locating means. This invention describes an intragastric balloon has an ellipsoid or like configuration so that the balloon that implanted in the stomach tends to rotate or rock only about one axis when a surgeon attempts to manipulate the balloon, for example, for the purpose of finding a filler valve and inserting a filler tube into it. For easy location, the filler valve is disposed on the equator. A retrieval tab is mounted to the exterior of the balloon, to permit capturing of the balloon and retrieval from the stomach, after the balloon has been deflated and is no longer desired for weight control purposes. Visual and x-ray opaque markers are located in the proximity of the valve and of the retrieval tab to facilitate their visualization with an endoscopic light when the balloon is in the stomach.
The difficulty with positioning leads to the additional concern of how to insure the delivered of the correct dose of the x-ray source. Providing a controlled dose of x-ray with an x-ray source inside a body lumen requires a precise means for determining the placement of the x-ray as well as the dose of the x-ray.
The present invention overcomes the difficulties associated with x-ray therapy and apparatus of the prior art by providing a guide wire with an x-ray transparent window that allows x-rays to pass therethrough to reach the target tissue.
This invention utilizes an x-ray transparent section of a guide wire through which x-rays pass without obstruction. The x-ray transparent section will typically be transparent to the eye, although the only requirement is that the section be transparent to x-rays. This x-ray transparent section allows the guide wire to guide the catheter aiding in positioning of the device inside a body lumen without impeding the irradiation process.
The invention also relates to a unique alignment system which allows the operator, using a visual endoscopic apparatus, to position a guide wire in a body lumen. A second positioning system comprises a unique marker system to position the catheter over the treatment area. A third positioning system uses a guide wire having a unique flag system. The flags are pre-calibrated with the marker and the x-ray source. Once positioned with the foregoing systems, the x-ray unit is used to irradiate the target tissue with irradiation which passes through the self-aligned x-ray transparent region of the guide wire.
The present invention also relates to endoscope having the guide wire and positioning system, to methods of manufacturing the devices, and to treating various diseases and conditions with the devise.
The invention is described in further detail below, with reference to the accompanying figures.